Steam tunnels for treating logs and method of treatment

ABSTRACT

Apparatus and method for uniformly heating and saturating logs or wood &#39;&#39;&#39;&#39;blocks&#39;&#39;&#39;&#39; in one or more tunnels to condition the same to be peeled into veneer. The tunnel has a conveyor for moving blocks therethrough in a single layer, and has steam nozzels above and below the path of travel of the blocks for subjecting the blocks to highly saturated steam while they are in the tunnel. The tunnel is divided into four zones, each having its own independent automatic control system for providing a prescribed heating and saturating treatment. The speed of the conveyor and the heating cycle are co-ordinated with the demand of the cutting lathe for continuous operation. An in-feed conveyor, including a &#39;&#39;&#39;&#39;kicker&#39;&#39;&#39;&#39; device, supplies blocks to a crowder conveyor, which crowds the blocks against each other ahead of the entrance to the tunnel. A transfer conveyor at the tunnel exit receives the treated blocks from a &#39;&#39;&#39;&#39;stop and loader&#39;&#39;&#39;&#39; device, which transfers the blocks from the tunnel conveyor to the transfer conveyor. Another &#39;&#39;&#39;&#39;kicker&#39;&#39;&#39;&#39; device kicks the block off the transfer conveyor onto a lathe in-feed deck to supply a lathe charger. Control means, which may be either manual or automatic, regulates the discharge of blocks from the tunnel and delivery thereof to the charger in-feed deck. Under automatic control, the lathe charger,in positioning a block in the lathe, operates a limit switch that effects the discharge of a block from the tunnel.

ijted @ates et all.

[75] inventors: C W. Gates; Lesley R. Gates, Vayne R. Davis, all of Gainesville, Fla. [73 J Assignee: Thomas E. Gates 8: Sons, llnc,

fiitirayl iafia {22! Filed: July 9, 1971 {21] Appl. No: 161,256

[52] US. Cl. 341/95, 34/201 [51] int. Cl F261) 3/00 [58] Field of Search 34/9.5, 13.4, 13.8, 34/201 [56] References Cited UNITED STATES PATENTS 2,892,261 6/1959 Hutchinson 34/9.5 2,464,429 3/1949 Barksdale 34/9.5 3,545,094 12/1970 Schvette et a1. 34/l3.4 1,519,287 12/1924 Woodson 34/201 Primary Examiner-John J. Camby (were Harry wtfsfilems [57] ABSTRACT Apparatus and method for uniformly heating and satufamed blocks in one or more tunnels to condition the same to be peeled into veneer. The tunnel has a conveyor for moving blocks therethrough in a single layer, and has steam nozzels above and below the path of travel of the blocks for subjecting the blocks to highly saturated steam while they are in the tunnel. The tunnel is divided into four zones, each having its own independent automatic control system for providing a prescribed heating and saturating treatment. The speed of the conveyor and the heating cycle are coordinated with the demand of the cutting lathe for continuous operation. An in-feed conveyor, including a kicker" device, supplies blocks to a crowder conveyor, which crowds the blocks against each other ahead of the entrance to the tunnel. A transfer conveyor at the tunnel exit receives the treated blocks from a stop and loader device, which transfers the blocks from the tunnel conveyor to the transfer conveyor. Another kicker device kicks the block off the transfer conveyor onto a lathe in-feed deck to supply a lathe charger. Control means, which may be either manual or automatic, regulates the discharge of blocks from the tunnel and delivery thereof to the charger infeed deck. Under automatic control, the lathe charger- ,in positioning a block in the lathe, operates a limit switch that effects the discharge of a block from the tunnel.

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saw 1BUF18 STEAM TUNNELS FOR TREATKNG LOGS AND METHOD OF TREATMENT BACKGROUND OF THE INVENTION in the past, difficulties have been encountered in the plywood and veneer industries in cutting or peeling logs or blocks to produce high quality veneer from wood of both hard and soft species. These problems are caused by the inherent characteristics of the wood fiber structure of the species. For example, the presence in the wood of hard or ingrown knots, alternating bands of soft spring wood and hard summer wood, and areas of cross-grain may all contribute to a lower recovery rate of veneer as the sheets are peeled at the lathe, unless the blocks have been properly preconditioned. Thus, in the peeling operation, the knots may break and fall from the sheet leaving undesirable holes, or cause the sheet to tear. The alternating bands of soft and hard wood tend to cause chatter at the lathe knife, thereby resulting in ridges or pock marks on the sheet, splits or cracks along its edge, or tears along the entire sheet surface.

In order to overcome these difficulties, it has become customary in the veneer industry to heat the logs or wood blocks in order to soften or plasticize them so that they can be more easily peeled into high quality veneer. The proper degree of heating and saturation of the wood softens the fibers, particularly the hard knots and rings of summer wood. Care is necessary in the heating and saturating of the blocks, since insufficient heat will not noticeably soften the blocks; whereas, excessive heat tends to destroy the wood fibers.

1. Field of the Invention The present invention relates to an apparatus and method for heating and plasticizing logs or wood blocks, and where a moisture depletion exists, to 'resaturate andheat the blocks to the proper state of plasticizing.for peeling into high quality veneer for use in r'naking plywood panels, etc.

- .2. Description of the Prior Art Various attempts have been made heretofore to provide methods and apparatus for treating logs or blocks to impart thereto the necessary heating and plasticizing to condition the blocks for peeling with a minimum amount of damage and waste.

For example, one prior method consisted in submerging the logs in a vat containing hot water between about 180 and 212 F. This method requires a great deal of time and is inherently slow because of the handling involved and the limited capacity of the vats. A less time consuming method requires the use of concrete steaming vaults, employing various heating mediums, such as, hot water sprays, dry steam, or a combination of dry steam and a hot water spray. These methods attempted to duplicate the results obtained by the earlier hot water immersion bathe. However, such methods do not provide complete moisture coverage of all of the logs or result in a uniform temperature and uniform degree of saturation throughout the log.

A more recent and more efiicient apparatus and method for treating logs to be cut into veneer is disclosed in Mortensen U.S. Pat. No. 3,448,530, which, while it employs a steam vault about 75 feet long, 14 feet high and 12 feet wide, nevertheless, carefully regulates the steaming and moisturizing of the logs according to their condition and the particular species of wood involved. The apparatus and method disclosed in the Mortensen patent operate quite satisfactorily, but the system is inefficient in the respect that the logs must be loaded into the vault and piled upon each other until the vault is full, and after conditioning be removed from the vault, by a fork lift. Further, siince the logs are stacked in the vault until the vault is full, a long period of time (about 5% hours to 8 hours) is required to condition all of the logs before any can be removed and delivered to a peeling lathe. The logs remaining in the vault must be steeped until removed to keep them in a soft and moist condition so that they will not dry out and harden up before they are used.

The principles of heating and saturating the logs disclosed in the Mortensen U.S. Pat. No. 3,448,530, are

employed in the treatment of the blocks as contemplated by the present invention, and such teachings of the Mortensen patent are hereby incorporated by reference. However, due to the novel tunnel design and conveyor system of the present invention, the block conditioning cycle is reduced to about 2 hours.

SUMMARY OF THE lNVENTlON The present invention is disclosed herein as embodying two tunnels disposed side by side, but this is by way of example only and not limitation, since the same principles are applicable to a single tunnel, or to more than two tunnels.

The foregoing objections and disadvantages of the prior art are overcome by the present invention, which provides for introducing the blocks into the steam tunnels by endless conveyors and carrying the blocks through the steam tunnels, also on endless conveyors, at a speed suitable to the capacity of the veneer lathe. More specifically, the logs are delivered to a conventional barker, which removes the bark therefrom, and are then delivered to an input conveyor having a saw associated therewith for cutting successive logs into blocks of suitable length (about 8% feet) to be received in the steam tunnels. The blocks supplied to the input conveyor are successively kicked off the input conveyor and onto crowder conveyors leading to the entrance to each tunnel. The crowder conveyors deliver the blocks to endless conveyors extending for the full length of tunnels, so that the blocks are carried through the tunnels at a desired speed. The crowder conveyors travel at a speed considerably faster than the tunnel conveyors so that the conveyor chains slip relative to the blocks and the blocks are crowded or held close against each other as they are supplied to the slower moving tunnel conveyor at theentrance to the steam tunnels.

Each steam tunnel is divided into four zones by flexible flaps. An inspection door in the roof portion of each zone provides ready access thereto. Highly saturated steam is speparately supplied to each zone of the tunnels so that the desired conditioning of the blocks occurs as they are moved through the successive zones in a single layer. Each zone has a condensate discharge outlet with a temperature sensor therein, and a vapor temperature sensor near the top of the zone. The conditioning of the blocks from the time that they enter until they leave the tunnels can be varied to meet operating conditions. but usually requires a total time of about two hours. In a typical cycle, the blocks may enter Zone 1 at a temperature as low as about 30F or lower in cold weather; or F, or higher in the summertime. Regardless of the temperature at which the 

1. In a method of heating and saturating wood blocks in an elongated enclosed area to condition the same for cutting into veneer, the steps comprising: introducing, supporting and moving blocks through the enclosed area; and subjecting the blocks while in said enclosed area to appropriate amounts of steam of high moisture content to progressively heat and saturate the blocks sufficiently to render the same suitable for cutting into veneer by the time that the blocks leave the enclosed area.
 2. The method defined in claim 1, including the step of: moving the blocks through the enclosed area in a single layer.
 3. The method defined in claim 1, including the step of: directing jets of steam simultaneously against the blocks from above and below the same.
 4. The method defined in claim 1, including the step of: maintaining the blocks crowded against each other while they are being moved through the enclosed area.
 5. The method defined in claim 1, including the step of: crowding the blocks against each other prior to introduction into the enclosed area.
 6. The method defined in claim 1, including the steps of: crowding the layer of blocks against each other prior to introduction into the enclosed area; and maintaining the blocks crowded together while moving them through the enclosed area.
 7. The method definEd in claim 1, including the steps of: removing the treated blocks from the enclosed area one at a time, and delivering the blocks to a lathe charger.
 8. The method defined in claim 2, including the steps of: maintaining the blocks crowded against each other while they are being moved through the enclosed area; removing the treated blocks one at a time from the enclosed area; and delivering the treated blocks to a lathe charger.
 9. The method defined in claim 2, including the steps of: providing at least one additional elongated enclosed area and supporting and moving a single layer of blocks through at least said one additional enclosed area; subjecting the blocks while in said additional enclosed area to appropriate amounts of steam of high moisture content to progressively heat and saturate the blocks sufficiently to render the same suitable for cutting into veneer by the time the blocks leave said additional enclosed area; and removing the treated blocks one at a time alternately from the enclosed area.
 10. The method defined in claim 9, including the steps of: delivering the removed blocks to a lathe charger to be successively positioned in a veneer lathe; and removing a treated block from one or the other of the enclosed areas each time that a block is positioned in the lathe.
 11. The method defined in claim 1, including the step of: dividing the elongated enclosed area lengthwise into a plurality of successive zones; and subjecting the blocks while in said zones to appropriate amounts of steam to impart a predetermined temperature and saturation thereto for each given zone.
 12. The method defined in claim 11, including the step of: draining condensate from each zone; and delivering steam to the separate zones in predetermined amounts corresponding to the temperature of the condensate draining from the respective zones.
 13. Apparatus for handling and conditioning wood blocks to be cut into veneer, comprising: an elongated treating tunnel having an entrance and an exit; a tunnel conveyor within said tunnel for receiving blocks, moving the blocks through said tunnel, and discharging the blocks at the exit of said tunnel; and means driving the tunnel conveyor including means operable for effecting intermittent movement of said tunnel conveyor for intermittently discharging said blocks from said tunnel.
 14. Apparatus as defined in claim 13, including means arranged to continuously deliver blocks to the entrance to the tunnel for further conveyance by the tunnel conveyor.
 15. Apparatus as defined in claim 13, including means for delivering blocks to the tunnel conveyor in a single layer.
 16. Apparatus as defined in claim 15, wherein the tunnel conveyor moves the blocks through the tunnel in a single layer; and wherein the tunnel has means for heating and saturating the blocks with moisture while being so moved.
 17. Apparatus as defined in claim 13, including means dividing the tunnel into a plurality of separate zones; and means separately heating and controlling the temperature in each zone.
 18. Apparatus as defined in claim 13, wherein the means operable to effect intermittent movement of the tunnel conveyor is a clutch.
 19. Apparatus as defined in claim 18, wherein the clutch is fluid pressure operated; a solenoid-operated valve connected with said clutch to control the flow of operating fluid thereto; control means for said solenoid-operated valve including a switch connected with said solenoid-operated valve to energize the same to thereby effect engagement of said clutch.
 20. Apparatus as defined in claim 19 including a transfer conveyor adjacent the discharge end of the tunnel conveyor; means arranged to drive said transfer conveyor, a stop and loader device disposed between the tunnel conveyor and the transfer conveyor for receiving a block from the tunnel conveyor and moving said block onto the transfer conveyor; means connected with said stop and loader device for operating the same; a NO switch positioned to be helD closed by the stop and loader device when in a position to accept a block from the tunnel conveyor; a NC switch positioned to be opened by the block after it is received in the stop and loader device, said NO and NC switches being connected in series and with the solenoid-operated valve; and wherein the switch is manually operable and has an ''''automatic'''' position wherein it is connected in series with said NO and NC switches, whereby the circuit to the solenoid-operated valve controlling the clutch is automatically completed upon the reception of a block in the stop and loader device.
 21. Apparatus as defined in claim 15, wherein the means for delivering blocks to the tunnel conveyor includes a crowder conveyor for crowding the blocks against each other; and means for continuously driving the crowder conveyor at a speed greater than the speed at which the tunnel conveyor travels, whereby to crowd the blocks against each in advance of the tunnel entrance and to maintain the blocks crowded against each other on the tunnel conveyor.
 22. Apparatus as defined in claim 21, in which the crowder conveyor has a receiving end; and a block input conveyor is positioned transversely to said crowder conveyor and adjacent to said receiving end for delivering blocks to said crowder conveyor; means for driving said input conveyor; and means operable to remove a block from the input conveyor and to deposit the same upon the crowder conveyor.
 23. Apparatus as defined in claim 22, including manually operable means controlling the operation of the block input conveyor.
 24. Apparatus as defined in claim 22, in which the means for removing the block from the input conveyor and depositing the same on the crowder conveyor includes a kicker device comprising arms having ends for engaging a block and kicking it off the input conveyor onto the crowder conveyor; a fluid pressure operated cylinder connected to actuate said arms; a solenoid-operated valve connected with said cylinder and controlling the supply and exhaust of operating fluid to said cylinder; and NO switch means connected with said solenoid-operated valve and being operable to energize said solenoid valve.
 25. Apparatus as defined in claim 24, wherein the switch means is mounted on the input conveyor in the path of movement of a block being carried by said input conveyor; and wherein the switch means is actuated by a block being conveyed on said input conveyor for energizing the solenoid-operated valve and effecting automatic operation of the kicker device.
 26. Apparatus as defined in claim 24, in which a block-stop device is mounted transversely to the input conveyor and comrpises a housing, a stop arm slidably supported in said housing so that it can be moved to a position to obstruct a block on the input conveyor, said stop arm having clearance in said housing allowing limited sidewise movement thereof in said housing, and wherein the switch means is mounted on said housing so as to be actuable to close by sidewise movement of said stop arm upon engagement of a block with said stop arm, an operating cylinder connected with said stop arm, a solenoid-operated valve connected to control the supply and exhaust of operating fluid to said cylinder, and a manually operable control switch connected with said solenoid-operated valve.
 27. Apparatus as defined in claim 13, including a transfer conveyor located at the exit of the tunnel for receiving blocks one at a time from the tunnel conveyor; means connected to drive said transfer conveyor; a stop and loader device disposed between the the discharge end of the tunnel conveyor and the transfer conveyor operable to transfer a block, delivered thereto by the tunnel conveyor, onto the transfer conveyor; and control means operable for actuating said stop and loader device to effect the loading of the block received from the tunnel conveyor onto the transfer conveyor.
 28. Apparatus as defined in claim 27, in which the drive means for the transfer conveyOr includes a reversible electric motor, whereby the transfer conveyor can be reversed in direction to reject a block that has been delivered thereto.
 29. Apparatus as defined in claim 27, wherein the stop and loader device comprises a pair of arms for receiving a block from the tunnel conveyor; means connected with said arms for actuating the same including a fluid pressure operated cylinder, a solenoid-operated valve connected with said cylinder for controlling the supply and exhaust of operating fluid thereto; and wherein the control means for the stop and loader device includes a switch connected with and controlling said solenoid-operated valve.
 30. Apparatus as defined in claim 29, wherein the switch can be manually actuated to energize the solenoid-operated valve to operate the stop and loader device.
 31. Apparatus as defined in claim 27, wherein the control means for the solenoid-operated valve is automatic and includes a NO switch that is held closed by the stop and loader while in a position to accept a block from the tunnel conveyor.
 32. Apparatus as defined in claim 27, wherein the control means for the solenoid-operated valve is automatic and includes a NC switch that is held open by a block in the stop and loader.
 33. Apparatus as defined in claim 27, wherein the control means for the solenoid-operated valve includes a NO switch that is held closed by the stop and loader while in a position to accept a block from the tunnel conveyor, and a NC switch that is held open by a block in the stop and loader, said switches being connected in a circuit in series with each other and with the solenoid-operated valve, and wherein the manual switch can be actuated to an ''''automatic'''' position in series with said NO and NC switches to enable automatic control of the stop and loader device, said manual switch when in a ''''manual'''' operating position being connected in shunt relation to said NO and NC switches.
 34. Apparatus as defined in claim 33, including a NO switch connected in the circuit that is momentarily energized by the stop and loader during discharging of a block therefrom.
 35. Apparatus as defined in claim 33, wherein the manually operated switch has an ''''automatic'''' position for enabling the stop and loader device to be automatically operated; and wherein a control relay and a NO switch are connected in a circuit with the manual-automatic switch and the solenoid-operated valve, said NO switch being arranged to be held closed momentarily by the stop and loader device during discharging of a block therefrom onto the transfer conveyor.
 36. Apparatus as defined in claim 35, including an infeed deck; a lathe; a lathe charger; and a NO limit switch momentarily actuated by the lathe charger in positioning a block in the lathe connected in circuit with the control relay and the NO switch for energizing the solenoid-operated valve to operate the stop and loader to supply a block to the transfer conveyor as another block is being positioned in the lathe.
 37. Apparatus as defined in claim 36, wherein a kicker device is mounted relative to the transfer conveyor at the infeed deck of the lathe charger, said kicker device including a pair of arms having ends for engaging a block and kicking it off the transfer conveyor onto the infeed deck, said kicker device further including a fluid pressure operated cylinder connected with said arms; a solenoid operated valve connected with said cylinder controlling the supply and exhaust of said operating fluid to said cylinder; a limit switch located in the path of travel of said transfer conveyor and being operable by a block being conveyed by said transfer conveyor, said switch being connected in a circuit with said solenoid-operated valve for automatically actuating said kicker device upon actuation of said limit switch by engagement therewith of a block on the transfer conveyor.
 38. Apparatus for treating wood blocks to condition the same to be cut into veneer, Comprising: a plurality of tunnels each having an entrance and an exit; a conveyor in each of said tunnels for moving a layer of blocks therethrough while being treated; independent drive means driving said tunnel conveyors; and a separately operable clutch connected with each drive means for independently controlling the operation of said tunnel conveyors.
 39. Apparatus as defined in claim 38, wherein the clutches are pneumatically operable and a solenoid-operated valve is connected with each of the clutches to energize the same; and a switch connected in circuit with each of the solenoid-operated valves and being operable to actuate the clutches as desired.
 40. Apparatus as defined in claim 38, in which the tunnels are arranged parallel with each other, a transfer conveyor located at the exit end of said tunnels; means including a stop and loader device associated with said transfer conveyor and with each tunnel for receiving blocks one at a time from said tunnels; and means for automatically operating said stop and loader devices.
 41. Apparatus as defined in claim 38, including an input conveyor for supplying blocks to the tunnels; the crowder conveyor between the input conveyor and one of the tunnels; a NO limit switch located adjacent to said crowder conveyor and being arranged to be operable by a block on the input conveyor; and a first kicker device including an operating cylinder and a solenoid-operated control valve connected with said cylinder and with said switch, for automatically kicking a block off the input conveyor onto said crowder conveyor.
 42. Apparatus as defined in claim 41, including a second crowder conveyor between the input conveyor and another of said plurality of tunnels; a stop arm mounted on the input conveyor adjacent to the second crowder conveyor; manually controlled means operable to cause said stop arm to assume a position obstructing movement of a block on the input conveyor; a NO switch arranged to be closed by movement of the stop arm when engaged by a block; a second kicker device similar to the first kicker device for kicking a block off the input conveyor and onto the second crowder conveyor; and a second solenoid-operated valve connected in circuit with the switch actuated by said stop arm for energizing said solenoid valve and automatically operating said second kicker device.
 43. Apparatus as defined in claim 42, including guide means alongside the crowder conveyors and guiding the blocks while enroute to the entrance to the respective tunnels.
 44. Apparatus for handling and conditioning wood blocks to be cut into veneer, comprising: an input conveyor for conveying blocks to be treated; manually controlled means driving said input conveyor; a plurality of crowder decks arranged side-by-side and at right angles to said input conveyors and having one end thereof adjacent to said input conveyor; means arranged to transfer blocks from said input conveyor onto the respective crowder decks; a crowder conveyor in each of said crowder decks having a receiving end to receive blocks from said input conveyor and also having a discharge end; means connected with each crowder conveyor for driving the same; a plurality of tunnels, one in line with each of said crowder conveyors, said tunnels having an entrance adjacent to the discharge end of said crowder conveyors and having an exit; a tunnel conveyor in each of said tunnels having a receiving end for receiving blocks from its respective crowder conveyor and having a discharge end for discharging blocks from said tunnels; means for intermittently and independently driving said tunnel conveyors at a speed less than the speed of said crowder conveyors; means in said tunnels for heating and saturating the blocks with moisture to condition the same to be cut into veneer while in transit through said tunnels; a stop and loader device at the exit of each of said tunnels arranged transversely to said tunnel conveyors to receive a block from the discharge end of said tunnel conveyOrs; a transfer conveyor arranged at right angles to the tunnel conveyors and parallel with said stop and loader devices, said transfer conveyor having a discharge end; means driving said transfer conveyor; said tunnel conveyor drive means including electrically actuated control elements; means for actuating the particular stop and loader device that has received a block from a given tunnel conveyor to cause said stop and loader device to transfer said block to said transfer conveyor; a lathe infeed deck located adjacent to the discharge end of said transfer conveyor; means arranged to move a block off the transfer conveyor onto the infeed deck; a lathe; a lathe charger arranged to receive a block from the infeed deck and to position said block in said lathe; means including a limit switch actuated by movement of said lathe charger in positioning a block in said lathe connected in circuit with said electrically operated control elements of said tunnel conveyor drive means for effecting operation of the tunnel conveyor driving means for discharging a block from successive tunnels each time that said lathe charger positions a block in said lathe. 